Information processing method, printing apparatus, and computer-readable medium for supressing light scattering

ABSTRACT

Print data is generated to form an image on a printing medium by superposing a plurality of types of printing materials in some or all pixels of an output image in an order complying with the intensities of the light scattering characteristics of the plurality of types of printing materials. The generated print data is transmitted to a printing apparatus.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an information processing method,printing apparatus, and computer-readable medium for generating printdata in a printing apparatus which forms an image on a printing mediumwith a plurality of types of printing materials.

2. Description of the Related Art

Recently, various types of printing apparatuses have been proposed asinformation output apparatuses for a word processor, personal computer,facsimile apparatus, and the like. The printing apparatus prints desiredinformation such as text and images on a sheet-like printing medium suchas paper or a film. Of these printing apparatuses, a printing apparatuswhich forms text and images on a printing medium by applying a printingmaterial to the printing medium has become commercially available. Atypical example of this printing apparatus is an inkjet printingapparatus. These days, the performance of inkjet printing apparatuseshas been improved to print not only text but also color images.

As the image quality of color inkjet printing apparatuses has improved,so-called photo printing has become popular for outputting digitalimages using the color inkjet printing apparatuses. As photo printinghas prevailed, preservation of printouts becomes important.

Conventionally, dye ink has been mainly used as a printing material inthe inkjet printing apparatus. However, the preservation properties ofdye ink are poor, so the color inkjet printing apparatus sometimes usespigment ink, which are known to have excellent preservation properties.

Some of the above-described inkjet printing apparatuses use a pluralityof types of inks, and reproduce multi-color, multi-tone images byforming a plurality of types of ink dots on top of each other on aprinting medium, as disclosed in Japanese Patent Laid-Open Nos.2003-54016 and 6-171111.

When the color is reproduced by discharging ink onto a printing medium,the reproduced color and glossiness sometimes change depending on theorder in which a plurality of types of inks are superposed. As the colorreproduction range is wider (colors in a wider range can be reproduced),a higher image quality can be achieved. According to a techniquedisclosed in Japanese Patent Laid-Open No. 2004-155181, colorreproduction ranges when superposing inks in all orders are measured inadvance, and the ink discharge order is controlled in accordance withthe measurement results.

Japanese Patent Laid-Open No. 2005-193463 discloses a technique ofsuppressing a decrease in glossiness by printing with inks in an orderin which an ink other than one having the highest density or an inkother than one having the lowest glossiness is superposed finally.

In practice, however, no conventional technique has made a closeexamination of the relationship between a concrete ink superpositionorder and the color reproduction range.

According to a method of measuring color gamuts by printing in all colororders in advance, as disclosed in Japanese Patent Laid-Open No.2004-155181, the number of processes abruptly increases as the number ofcolors used, the number of printing media, and the number of print modesincrease. Hence, this method is not practical in multi-color printers.

SUMMARY OF THE INVENTION

The present invention has been made to overcome the conventionaldrawbacks, and provides an information processing method, printingapparatus, and computer-readable medium capable of suppressingscattering of light in an unnecessary wavelength band to the outside,and widening the color reproduction range of high-saturation,high-density portions.

According to the first aspect of the present invention, there isprovided an information processing method of generating print data in aprinting apparatus which forms an image on a printing medium with aplurality of types of printing materials, the method comprising: agenerating step of generating print data to form an image on theprinting medium by superposing the plurality of types of printingmaterials in at least some pixels of an output image in an ordercomplying with intensities of light scattering characteristics of theplurality of types of printing materials; and a transmission step oftransmitting the print data generated in the generating step to theprinting apparatus.

According to the second aspect of the present invention, there isprovided an information processing method of generating print data in aprinting apparatus which forms an image on a printing medium with aplurality of types of printing materials, the method comprising: anacquisition step of acquiring light scattering characteristicinformation of all printing materials used in the printing apparatus; adecision step of deciding, in accordance with the light scatteringcharacteristic information acquired in the acquisition step, an order inwhich the plurality of types of printing materials are superposed in atleast some pixels of an output image to form an image on the printingmedium; and a generation step of generating print data to form an imageon the printing medium by superposing the plurality of types of printingmaterials in the order decided in the decision step.

According to the third aspect of the present invention, there isprovided a printing apparatus that forms an image on a printing mediumwith a plurality of types of printing materials, the printing apparatuscomprising: a generating unit configured to generate print data forforming an image on the printing medium by superposing the plurality oftypes of printing materials in at least some pixels of an output imagein an order complying with intensities of light scatteringcharacteristics of the plurality of types of printing materials; and aprinting unit configured to print based on the print data.

According to the fourth aspect of the present invention, there isprovided a printing apparatus that forms an image on a printing mediumwith a plurality of types of printing materials, the printing apparatuscomprising: an acquisition unit configured to acquire light scatteringcharacteristic information of all printing materials used in theprinting apparatus; a decision unit configured to decide, in accordancewith the light scattering characteristic information acquired by theacquisition unit, an order in which the plurality of types of printingmaterials are superposed in at least some pixels of an output image toform an image on the printing medium; a generation unit configured togenerate print data for forming an image on the printing medium bysuperposing the plurality of types of printing materials in the orderdecided by the decision unit; and a printing unit configured to printbased on the print data.

According to the fifth aspect of the present invention, there isprovided a computer-readable medium for storing a program which causes acomputer to execute information processing of generating print data in aprinting apparatus which forms an image on a printing medium with aplurality of types of printing materials, the program causing thecomputer to execute a generating step of generating print data to forman image on the printing medium by superposing the plurality of types ofprinting materials in at least some pixels of an output image in anorder complying with intensities of light scattering characteristics ofthe plurality of types of printing materials, and a transmission step oftransmitting the print data generated in the generating step to theprinting apparatus.

According to the sixth aspect of the present invention, there isprovided a computer-readable medium for storing a program which causes acomputer to execute information processing of generating print data in aprinting apparatus which forms an image on a printing medium with aplurality of types of printing materials, the program causing thecomputer to execute an acquisition step of acquiring light scatteringcharacteristic information of all printing materials used in theprinting apparatus, a decision step of deciding, in accordance with thelight scattering characteristic information acquired in the acquisitionstep, an order in which the plurality of types of printing materials aresuperposed in at least some pixels of an output image to form an imageon the printing medium, and a generation step of generating print datato form an image on the printing medium by superposing the plurality oftypes of printing materials in the order decided in the decision step.

According the seventh aspect of the present invention, there is provideda printing apparatus which forms an image on a printing medium with aplurality of types of printing materials, the apparatus comprising: aprinthead having a plurality of nozzle arrays for discharging theplurality of types of printing materials; and a main-scanning drive unitconfigured to execute main scanning by driving at least either of theprinthead and a printing medium, wherein at least some of the nozzlearrays of the printhead are aligned in order in a traveling direction ofmain scanning of the printhead in accordance with an order in whichprinting materials discharged from the nozzle arrays are superposed, andthe order in which the printing materials are superposed complies withlight scattering characteristic information.

Further features of the present invention will be apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing an example of the configuration of aprinting system according to the first embodiment of the presentinvention;

FIG. 1B is a block diagram showing the hardware configuration of a hostapparatus according to the first embodiment of the present invention;

FIG. 2 is a view showing a print setup window serving as a printerdriver UI according to the first embodiment of the present invention;

FIGS. 3A to 3D are schematic views for explaining multipass printingaccording to the first embodiment of the present invention;

FIGS. 4A to 4C are views showing the mask patterns of respective colorsused when a mode in which the superposition order of color inks iscontrolled is selected in 4-pass printing according to the firstembodiment of the present invention;

FIG. 5 is a sectional view showing a state in which inks are depositedaccording to the first embodiment of the present invention;

FIG. 6 is a table showing the print ratio of each pass for each colorgroup in a pass mask used in the second embodiment of the presentinvention;

FIG. 7 is an exploded perspective view showing a printhead used in thethird embodiment of the present invention; and

FIG. 8 is a plan view showing a nozzle arrangement on a printing elementsubstrate according to the third embodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail with reference to the drawings. It should be noted that therelative arrangement of the components, the numerical expressions andnumerical values set forth in these embodiments do not limit the scopeof the present invention unless it is specifically stated otherwise.

First Embodiment

[Outline of Printing System]

FIG. 1A is a block diagram showing an example of the configuration of aprinting system according to the first embodiment of the presentinvention.

The printing system includes an inkjet printer (printing apparatus) 102,and a host apparatus (computer or information processing apparatus(image processing apparatus)) 101.

The inkjet printer (to be simply referred to as a printer hereinafter)102 prints with three pigment inks: cyan C, magenta M, and yellow Y (aplurality of types of printing materials). For this purpose, the printer102 uses a printhead 10 for discharging these three color inks. Theprinthead 10 has a plurality of nozzle arrays for discharging aplurality of types of printing materials to the entire width of aprinting region in one direction on a printing medium.

The printer 102 includes a main-scanning drive unit which executes mainscanning by driving at least either the printhead 10 or a printingmedium. Depending on the configuration, the printer 102 includes asub-scanning drive unit which performs sub-scanning by driving at leasteither the printhead 10 or a printing medium each time main scanningends. These drive units are implemented by a head drive circuit 9.

An application program 1 and printer driver 11 run on the operatingsystem (OS) of the host apparatus 101. The application program 1 createsand edits image data to be printed by the printer 102.

Image data or image data before editing can be input to the hostapparatus 101 via a variety of media. For example, JPEG image dataobtained by a digital camera may also be input via a memory card. TIFFimage data scanned by a scanner or image data recorded on a CD-ROM mayalso be input. Needless to say, image data may also be downloaded from aserver or Web site on a network such as the Internet.

The host apparatus 101 displays input image data on a monitor 103. Theuser of the host apparatus 101 edits and processes image data via anoperation window that is generated by the application program 1 anddisplayed on the monitor 103, and he designates printing. In accordancewith this designation, the application program 1 (or OS) converts theimage data into sRGB image data (8 bits for each color), and outputs thesRGB image data to the printer driver 11.

The printer driver 11 executes color gamut mapping for image data inputfrom a color matching processing unit 2. The color matching processingunit 2 converts RGB data into RGB data in a printer color gamut byinterpolation using a three-dimensional LUT (3D LUT) representing therelationship between a color gamut reproduced by sRGB image data and acolor gamut (printer color gamut) reproducible by the printer 102.

A color separation processing unit 3 generates color separation data C,M, and Y (8 bits for each color) corresponding to a combination of inkswhich reproduce a color represented by RGB data mapped in the colorgamut. Similar to processing by the color matching processing unit 2,the color separation processing unit 3 executes this processing byinterpolation using a 3D LUT.

A gamma (γ) correction unit 4 performs gamma correction to convert thetone value of each color data of color separation data C, M, and Yobtained by the color separation processing unit 3. More specifically,the γ correction unit 4 converts the color separation data C, M, and Yto make them correspond to the tone characteristics of the printer 102by using a one-dimensional LUT (1D LUT) corresponding to the tonecharacteristics of respective color inks in the printer 102.

A halftoning unit 5 quantizes each of the color separation data C, M,and Y (8 bits for each color) into 4-bit data by using, for example,error diffusion. The 4-bit data serves as an index representing a dotlayout pattern in the printer 102.

A print data generation unit 6 generates print data by adding printcontrol information to 4-bit index data.

The hardware configuration of the host apparatus 101 will be explainedwith reference to FIG. 1B.

FIG. 1B is a block diagram showing the hardware configuration of thehost apparatus according to the first embodiment of the presentinvention.

In FIG. 1B, a CPU 1201 controls the operation of the overall hostapparatus 101 in accordance with programs stored in a RAM 1202 and ROM1203. The RAM 1202 is used as the main memory of the CPU 1201, and aprogram to be executed by the CPU 1201 is loaded into the RAM 1202. TheRAM 1202 provides a work area for temporarily saving various data in acontrol operation by the CPU 1201. The ROM 1203 stores a boot programand various data in a nonvolatile way.

The monitor 103 includes a display unit such as a CRT or liquid crystaldisplay, and is used to display data to be processed and a UI window tobe described later. An input unit 1205 includes pointing devices such asa keyboard and mouse, and is used to input various data and commands bya user operation.

An external storage apparatus 1206 is a large-capacity storage apparatussuch as a hard disk. An OS, the application program 1, the printerdriver 11, data, and the like are installed in advance in the externalstorage apparatus 1206. When activation of a program is designated, theprogram is loaded into the RAM 1202 and executed.

A network interface (I/F) 1207 controls an interface with a network 1209such as a LAN. The printer 102 and a variety of input/output devices areconnected to the network 1209. An input/output port 1208 is an interfacesuch as a USB or IEEE1394 interface.

Processes (information processing method) by the above-mentionedapplication program 1 and printer driver 11 are achieved by executingthe programs of the processes by the CPU 1201. The programs are loadedfrom the ROM 1203 or external storage apparatus 1206 into the RAM 1202,and executed. When executing the programs, the RAM 1202 is used as thework area of the CPU 1201.

In the printer 102, a dot layout patterning processing unit 7 and maskdata conversion processing unit 8 process print data input from the hostapparatus 101.

The dot layout patterning processing unit 7 lays out dots in accordancewith a dot layout pattern corresponding to 4-bit index data (tone valueinformation) for each pixel of an actual print image. More specifically,the dot layout patterning processing unit 7 assigns a dot layout patterncorresponding to the tone value of a pixel to each pixel expressed by4-bit data. The dot layout patterning processing unit 7 defines the dotON/OFF state of each of areas in each pixel, and arranges 1-bitdischarge data “1” or “0” for each area.

The mask data conversion processing unit 8 executes mask processing for1-bit discharge data. More specifically, the mask data conversionprocessing unit 8 executes processing using a mask corresponding to eachscanning to generate discharge data of each scanning for completingprinting by the printhead 10 by a plurality of number of scanningoperations in a scanning region (to be referred to as a “band”hereinafter) of a predetermined width in the sub-scanning direction.

Details of the mask data conversion processing unit 8 will be describedlater. The printhead 10 is formed by arraying, in the main scanningdirection, a plurality of printing elements for discharging, forexample, C, M, and Y color inks. The sub-scanning direction is adirection perpendicular to the main scanning direction which is aprinting medium conveyance direction.

Discharge data (discharge data C, M, and for respective colors)generated for each scanning by the mask data conversion processing unit8 are transmitted to the head drive circuit 9 at an appropriate timing.The head drive circuit 9 drives the printhead 10 to discharge each inkin accordance with the discharge data.

The processes of the dot layout patterning processing unit 7 and maskdata conversion processing unit 8 in the printer 102 are executed underthe control of a CPU which forms the control unit of the printer 102using a dedicated hardware circuit. The CPU of the printer 102 may alsoperform these processes in accordance with programs, or for example, theprinter driver 11 of the host apparatus 101 may also perform them.

The host apparatus 101 which executes processes shown in FIG. 1 is notlimited to a computer. For example, the printer 102 may also execute theprocesses of the host apparatus 101.

In the first embodiment, a “pixel” is a minimum unit capable ofexpressing a tone, and also a minimum unit to undergo multilevel dataimage processing, and processes of the color matching processing unit 2,color separation processing unit 3, γ correction unit 4, halftoning unit5, and the like. One pixel in the dot layout patterning processing unit7 corresponds a pattern of 4×4 squares, and each square in one pixelwill be called an area. The area is a minimum unit capable of definingthe dot ON/OFF state.

In association with this, “image data” in the color matching processingunit 2, color separation processing unit 3, and γ correction unit 4means a set of pixels to be processed, and each pixel is data whosecontents are, for example, an 8-bit tone value. “Pixel data” in thehalftoning unit 5 means pixel data itself to be processed. Thehalftoning unit 5 converts the 8-bit pixel data into pixel data (indexdata) whose contents are a 4-bit tone value.

[Printer Driver UI]

An example of a printer driver UI (User Interface) for controlling theprinter driver 11 in FIG. 1 according to the first embodiment will beexplained with reference to FIG. 2.

FIG. 2 is a view showing a print setup window serving as a printerdriver UI according to the first embodiment of the present invention.

An input text box 202 is a control box for designating/inputting desiredimage data to be printed. Information such as the file name of imagedata is input to the input text box 202. A combo box 203 is a controlbox for selecting a printing medium used to print. The combo box 203allows the user to select an arbitrary printing medium from all types ofprinting media available in the printer 102.

A group box 204 is a control box for alternatively selecting a radiobutton 205 or 206. The group box 204 has a function of allowing the userto select only either the radio button 205 or 206.

The radio button 205 is used to select a mode which gives priority tovividness (color reproduction range). When the radio button 205 isselected (checked), the print data generation unit 6 adds, to printdata, print control information for controlling the superposition orderof color inks. The radio button 206 is used to select a mode which givespriority to the print speed. When the radio button 206 is selected(checked), the print data generation unit 6 adds, to print data, printcontrol information for shortening the print time without controllingthe superposition order of color inks. That is, the radio buttons 205and 206 function as control buttons for determining whether to executecolor ink superposition order control processing.

A print button 207 is a control button for setting, as print conditions,various settings made in a print setup window 201, storing them in theRAM 1202, and designating execution of printing on the basis of theprint conditions. More specifically, the print button 207 is used totransmit, to the printer driver 11, image data and print conditionsassociated with color ink superposition order control. A cancel button208 is a control button for canceling various settings in the printsetup window 201.

Various control boxes and buttons such as the text box, combo box, radiobutton, and group box in the print setup window 201 are merely examples.Other objects can also be employed as long as they have the samefunctions.

[Mask Data Conversion Processing]

FIGS. 3A to 3D are schematic views for explaining multipass printingaccording to the first embodiment of the present invention.

Multipass printing is generally applied to serial inkjet printers.Multipass printing forms an image step by step by a plurality of printscanning operations in a single image region on a printing medium.

FIG. 3A shows the state of a printing medium after the first printscanning is done. Dots 301 are landed by the first print scanning. Inthis example, the dots 301 are printed without overlapping each other.FIG. 3B shows the state of the printing medium after the second printscanning is done. Dots 302 are printed by the second print scanning.FIG. 3C shows the state of the printing medium after the third printscanning is done. FIG. 3D shows the state of the printing medium afterthe fourth print scanning is done. Dots 303 and 304 are landed by thethird and fourth print scanning operations.

Printing in a single image region is completed by four print scanningoperations. An area printable by each print scanning is decided by, forexample, ANDing print data and binary data called a mask pattern.

Multipass printing for completing printing in a single image region by nprint scanning operations will be defined as n-pass printing. Printingcompleted by four print scanning operations in a single image region isexpressed as 4-pass printing.

In multipass printing, a printing medium is conveyed at an intervalbetween print scanning operations, so ink droplets are applied to theprinting medium at a predetermined time interval. Printing on even aprinting medium whose pigment ink absorption speed is low, such as plainpaper, can proceed while drying applied ink droplets little by little.Thus, a high-quality result can be obtained in terms of fixation.

Since a printing medium is conveyed at an interval between printscanning operations, printing elements on the printhead for printing ina single image region change between print scanning operations. Even ifdischarge varies between printing elements, the variations can bedistributed to make them less conspicuous on an image.

At the boundary between print scanning operations, a white or blackstreak may appear owing to variations in conveyance amount. However,multipass printing can make even such a streak less conspicuous on animage.

Variations in discharge of each printing element and variations inconveyance amount are image degradation factors which are inevitablygenerated in accordance with the manufacturing process and precision.Hence, the above-described multipass printing is an important printingtechnique for maintaining the image quality, and is generally employedin a serial inkjet printer.

An example of a mask pattern when the mode in which the superpositionorder of color inks is controlled (mode which gives priority tovividness) is selected (when the radio button 205 of the print setupwindow 201 in FIG. 2 is selected) will be explained with reference toFIGS. 4A to 4C.

FIGS. 4A to 4C are views showing the mask patterns of respective colorsused when the mode in which the superposition order of color inks iscontrolled is selected in 4-pass printing according to the firstembodiment of the present invention.

In the first embodiment, the light scattering characteristic of eachcolor ink is measured in advance to obtain the result that Y ink has thehighest light scattering characteristic and M ink has the lowest lightscattering characteristic.

The light scattering characteristic of each color ink may also be storedas light scattering characteristic information in the external storageapparatus 1206 of the host apparatus 101 or the internal memory of theprinter 102. If necessary, the printer driver 11 of the host apparatus101 can acquire light scattering characteristic information from thestorage apparatus.

In processing according to the first embodiment to decide an order inwhich printing materials are superposed, the superposition order ofcolor inks is decided in accordance with only the light scatteringintensity. The superposition order is decided to print Y ink having highlight scattering intensity on the lowest layer, and M ink having lowlight scattering intensity on the uppermost layer.

More specifically, as processing (superposition order controlprocessing) which gives priority to vividness, the printer driver 11(print data generation unit 6) decides an ink superposition order usinglight scattering characteristic information of each color acquired fromthe storage apparatus, so as to print by superposing inks in an order inwhich light scattering hardly occurs. The print data generation unit 6generates print data such that an ink having the lowest light scatteringintensity in one pixel of an image is superposed at the top on aprinting medium. This can suppress generation of light scattering of anoutput image formed on a printing medium.

The print data can also be generated for some or all pixels of an outputimage in accordance with the application purpose.

Each square shown in FIGS. 4A to 4C represents a region (area) where oneink dot is printed. FIGS. 4A to 4C show a mask pattern in 4×4=16 areas.In actual printing, a combination of 4×4-square mask patterns shown inFIGS. 4A to 4C is repeated in both the vertical and horizontaldirections. These mask patterns are stored in the internal memory of theprinter 102.

In a printing operation, print data sampled in accordance with the maskpattern of the first pass is printed by the first print scanning. Bysecond to sixth print scanning operations, print data sampled inaccordance with corresponding mask patterns are printed. The maskpatterns of the first to sixth passes for each color are complementaryto each other. Thus, all image data are printed by six print scanningoperations in a single image region on a printing medium.

As shown in FIGS. 4A to 4C, mask patterns for each color in the firstembodiment complete printing by four successive print scanningoperations among six print scanning operations. Y ink is printed by thefirst to fourth passes (FIG. 4A), and is not printed by the fifth andsixth passes. C ink is printed by the second to fifth passes, and is notprinted by the first and sixth passes (FIG. 4B). M ink is printed by thethird to sixth passes, and is not printed by the first and second passes(FIG. 4C).

The mask patterns of the first to fourth passes in a Y ink pass mask(FIG. 4A) are the same as those of the second to fifth passes in a C inkpass mask (FIG. 4B) and those of the third to sixth passes in an M inkpass mask (FIG. 4C). In other words, the mask pattern of each color isobtained by shifting the start position of a single pattern by one pass.

In all areas, Y ink is completely printed by the mth pass (m is aninteger of 1 to 4), C ink is completely printed by the (m+1)th pass, andM ink is completely printed by the (m+2)th pass. Printing can be done ina fixed superposition order of color inks.

In each pass, the mask patterns of the respective colors are exclusiveto each other. Thus, ink dots of a plurality of colors are not printedin a single area by the same pass, and a high-quality fixing result,which is an original purpose of multipass printing, can be obtained.

In the first embodiment, when printing an image in black (so-calledcomposite black) using three, C, M, and Y inks, a Y ink dot 502, C inkdot 503, and M ink dot 504 are stacked from the bottom on a printingmedium 501, as shown in FIG. 5.

Light which enters from the surface (upper side in FIG. 5) of a printingmedium and is scattered by a Y ink dot to the surface of the printingmedium is absorbed in C and M ink dots on the incoming and exit paths.As a result, scattered light is hardly observed from the outside,obtaining a higher-density black image.

When printing is done in an order in which a Y ink dot is superposed atthe top, unlike the first embodiment, light which enters from thesurface of a printing medium and is scattered by a Y ink dot to thesurface of the printing medium is not absorbed in C and M ink dots belowthe Y ink dot. Thus, strong light scattered by the Y ink dot is observedfrom the outside, decreasing the density of a black image and reducingthe color reproduction range.

Also when printing a high-saturation image with a mixture of two ofthree, C, M, and Y inks, an ink dot having high light scatteringintensity is printed on a lower layer, suppressing scattered light of anunnecessary wavelength band and obtaining a higher-saturation image.

In the first embodiment, the dot print ratio (the number of areas to beprinted) is equal between respective passes in four mask patters used toprint among mask patterns for each color. However, the print ratios ofrespective passes may also be different as long as the ink printingorder in each area can be controlled. For example, the print ratio of anintermediate pass may also be increased to, for example, reduce theinfluence of an air flow at the end of the printhead.

The first embodiment has described mask patterns each of 4×4 squares forcompleting printing by four scanning operations for each color, but thepresent invention is not limited to this. For example, even pass maskshaving another form can obtain the same effects as long as the inksuperposition order in each area is controlled. Such pass masks alsofall within the scope of the present invention. For example, the unit ofthe mask pattern may be areas in an arbitrary range. Printing in eachcolor may also be done by a smaller or larger number of scanningoperations.

The ink superposition order in the first embodiment is merely anexample, and another order also falls within the scope of the presentinvention as long as the superposition order is selected in accordancewith the light scattering characteristic (light scattering intensity).The superposition order of color inks is decided not only from the lightscattering characteristic, but also together with another characteristicinformation such as glossiness characteristic information, bronzecharacteristic information, or fixation of all printing materials usedin a printer. This also falls within the scope of the present invention.

Ink colors are not limited to C, M, and Y, and other color inks or adifferent number of inks may also be used as long as a plurality ofcolors are used. For example, when a light color ink is used, arelatively large amount of ink is used to reproduce even a low-densitycolor. The ratio at which an underlying ink having high light scatteringintensity is covered increases, so the present invention is preferablyapplied.

When a spot color ink is used, it is printed at the top because the spotcolor ink can efficiently absorb light scattered by a complementarycolor ink, thereby more effectively practicing the present invention.

Light scattering characteristic information may also be acquired from,for example, a print result of printing single-color solid patch imageswith all inks used in the printer 102 while the host apparatus 101controls the printer 102. That is, the host apparatus 101 controls ameasurement device (not shown) connected to it, and the measurementdevice measures the light scattering characteristics of single-colorsolid patch images in all colors printed on a printing medium, therebyacquiring light scattering characteristic information.

Light scattering characteristic information may also be that of a liquidprinting material or a diluted liquid of the printing material.

Light scattering characteristic information may also be estimated fromthe composition of a printing material.

The printing material may also include a combination of two or moretypes of printing materials having the same hue and different densities.In this case, a printing material having low density in a combination oftwo or more types of printing materials having the same hue anddifferent densities is preferably printed on a relatively upper layer.

A plurality of types of printing materials include at least one type ofprinting material of a spot color having a hue between arbitrary two ofprinting materials of cyan, magenta, and yellow basic colors. In thiscase, the printing material of the spot color is preferably printed on alayer above the printing materials of the basic colors.

As described above, the first embodiment can widen the colorreproduction range and improve image quality by controlling thesuperposition order of color inks in accordance with the lightscattering characteristics of the inks.

It can be controlled to superpose a plurality of types of printingmaterials such that a printing material having low light scatteringintensity is superposed on an upper layer. The first embodiment can,therefore, suppress scattering of light in an unnecessary wavelengthband to the outside, and widen the color reproduction range ofhigh-saturation, high-density portions.

Second Embodiment

A printer according to the second embodiment adopts a total of 11colors: cyan C, magenta M, yellow Y, black K, light colors includingphoto cyan Pc, photo magenta Pm, gray Gy, and photo gray Pgy, and spotcolors including red R, green G, and blue B. A printing system accordingto the second embodiment is identical to that in the first embodiment. Acolor separation processing unit 3 is extended to generate datacorresponding to the 11 color inks.

As described above, multipass printing has an effect of distributingvarious noise components, and an effect of obtaining a high-qualityimage even with a combination of an ink and printing medium having lowabsorption speed. These effects are enhanced as the number of passesincreases. However, the print speed decreases in proportion to thenumber of passes.

When pass masks described in the first embodiment are applied, thenumber of actual passes for each color is four, but six passes arerequired as the total number of print scanning operations, decreasingthe print speed regardless of the effects of multipass printing. As thenumber of inks increases, the total number of necessary print scanningoperations further increases. When a printhead capable of discharging 11color inks is mounted, like the second embodiment, a total of 14 printscanning operations are necessary in the method of the first embodiment.

From this, the second embodiment will explain an arrangement whichcontrols the ink superposition order by changing the print ratio of eachcolor ink dot on each pass without increasing the total number ofpasses.

The 11 color inks are classified into three groups in accordance withthe light scattering characteristic. Group 1 is a group of inks havinghigh light scattering characteristic, and includes C, M, and Y inks.Group 3 is a group of inks having low light scattering characteristic,and includes Bk, R, G, and B inks. Group 2 is a group of inks havingintermediate light scattering characteristic, and includes Pc, Pm, Gy,and Lgy inks.

FIG. 6 is a table showing the print ratio of each pass for each colorgroup in a pass mask used in the second embodiment of the presentinvention.

The mask patterns actually used are created to be exclusive betweenpasses in accordance with print ratios shown in FIG. 6, and are storedin a printer 102.

The print ratio of each color ink for each pass is decided in accordancewith the light scattering characteristic of the color ink. The printratio of a relatively early pass is set high for a pass mask used forgroup 1 having high light scattering characteristic. The print ratio ofa relatively late pass is set high for a pass mask used for group 3having low light scattering characteristic. The print ratio of anintermediate pass is set high for a pass mask used for group 2 havingintermediate light scattering characteristic.

In this case, the ink superposition order cannot be the same between allpixels. However, inks having high light scattering characteristic can beprinted mainly on lower layers, and inks having low light scatteringcharacteristic can be printed mainly on upper layers as a whole.

In the second embodiment, printing is completed by four print scanningoperations for each color. Since printing starts and ends simultaneouslyfor the respective colors, printing can be completed by a total of fourscanning operations. In this manner, the superposition order of colorinks can be controlled without increasing the total number of passes.

In the second embodiment, the print ratios of respective passes forgroup 1 and 3 monotonically increase or decrease, but the change of theprint ratio is not limited to this as long as the superposition order ofcolor inks can be controlled. For example, the print ratios of passesother than the first and final passes may also be maximized to, forexample, reduce the influence of an air flow at the end of theprinthead.

The superposition order of printing materials may also be decided inaccordance with the light scattering characteristic for only a portionhaving a color saturation higher than a predetermined one in each hueand brightness in a color gamut reproducible by the printer 102.

If a slight decrease in print speed is permitted and priority is givento higher image quality, printing with a printing material to be printedon a relatively lower layer preferably starts in main scanning executedrelatively early among N main scanning operations in a single region ofan image. Printing with a printing material printed on a relativelylower layer is preferably completed in main scanning executed relativelyearly among N main scanning operations in a single region of an image.

As described above, the second embodiment can widen the colorreproduction range and increase the print speed by changing the printratio of the pass mask of each color for each pass in accordance withthe light scattering characteristic.

Third Embodiment

The third embodiment employs a printing system shown in FIG. 1, similarto the first embodiment. Also, the third embodiment uses the same inksas those in the first embodiment.

An inkjet printer used in the third embodiment forms an image byperforming main scanning to drive a printhead on a stationary printingmedium, and sub-scanning to drive a printing medium in a directionperpendicular to the main scanning direction every time one mainscanning ends. The inkjet printer also performs so-called bi-directionalprinting to discharge ink in main scanning in both forward and returnpasses. In the following description, each of forward and return passesis handled as one main scanning.

FIG. 7 is an exploded perspective view showing a printhead used in thethird embodiment of the present invention.

In FIG. 7, a head cartridge 701 of the printhead includes a firstprinting element substrate 703, second printing element substrate 704,first plate 705, second plate 709, and printed circuit board 707. Thehead cartridge 701 further includes a tank holder 710, a channel formingmember 712, filters 713, and sealing rubber members 714.

The first printing element substrate 703 and second printing elementsubstrate 704 are Si substrates. A plurality of printing elements(nozzles) for discharging ink are formed by photolithography on onesurface of each Si substrate. An electric wiring line of AI or the likefor supplying power to each printing element is formed by a film formingtechnique. A plurality of ink channels corresponding to respectiveprinting elements are also formed by photolithography. Ink supply portsfor supplying ink to a plurality of ink channels are formed to be openin the lower surfaces of the first printing element substrate 703 andsecond printing element substrate 704.

FIG. 8 is a plan view showing a nozzle arrangement on the printingelement substrate according to the third embodiment of the presentinvention.

On the plate 709, nozzle arrays in which nozzles for discharging an inkof the same color are aligned in a direction perpendicular to the mainscanning direction are arranged at two portions for each color. Nozzlearrays 802 and 807 discharge Y ink, nozzle arrays 803 and 806 dischargeC ink, and nozzle arrays 804 and 805 discharge M ink. The three nozzlearrays 802 to 804 are driven in forward main scanning, and the threenozzle arrays 805 to 807 are driven in backward main scanning. That is,in both forward and return passes, Y ink nozzles discharge ink on thefront side in the traveling direction of main scanning, and M inknozzles discharge ink on the rear side in the traveling direction.

That is, some or all of the nozzle arrays of the printhead arepreferably aligned in order in the traveling direction of main scanningof the printhead in accordance with an order in which printing materialsdischarged from the nozzle arrays are superposed.

Main scanning includes forward main scanning of driving at least eitherthe printhead or a printing medium in a predetermined direction, andbackward main scanning of driving at least either the printhead or aprinting medium in a direction opposite to that of forward mainscanning.

At least some of the nozzle arrays of the printhead are arrangedseparately as forward pass nozzle arrays in which the nozzle arrays arealigned in order in the traveling direction of forward main scanning,and return pass nozzle arrays in which the nozzle arrays are aligned inorder in the traveling direction of backward main scanning.

With this arrangement, even when inks of a plurality of colors aredischarged to a single pixel in one main scanning, Y ink is dischargedfirst and M ink is discharged last, thereby controlling the landingorder of inks on a printing medium. The superposition order of colorinks can be controlled to widen the color reproduction range withoutincreasing the number of passes.

In the third embodiment, only the ink superposition order is controlledin accordance with the arrangement order of nozzle arrays. However, acombination of this control method and another one also falls within thescope of the present invention. For example, a combination of thecontrol method in the third embodiment and superposition order controlpremised on multipass printing as described in the first or secondembodiment also falls within the scope of the present invention.

The third embodiment can control the superposition order of color inkswithout performing multipass printing.

As described above, the third embodiment can widen the colorreproduction range and increase the print speed by deciding thearrangement order of ink nozzles on the printhead in accordance with thelight scattering characteristic.

The present invention can be implemented in a variety of forms. Forexample, the present invention can be implemented in the forms of aprinting method and printing apparatus, a printing control method andprinting control apparatus, and software for implementing the functionsof these methods and apparatuses. As other forms, the present inventioncan be implemented in the forms of a recording medium which records thesoftware, and data signals which include the software and are embodiedin a carrier.

In particular, the printing method suffices to stack a plurality oftypes of printing materials on the surface of a printing medium, andvarious printing methods accompanied by plate making for each printingmaterial are also available. The printing method may also be an imageprinting method accompanied by no plate making, such as an inkjetmethod, electrophotographic method, thermal transfer method, or dotimpact method. An inkjet printer may also be a serial printer in whichthe printhead scans the printing region in longitudinal and lateraldirections, or a line head printer in which nozzles are arranged alongthe entire width of a printing region, and the printhead scans in onlyone direction.

The present invention can provide an information processing method,apparatus, and program capable of suppressing scattering of light in anunnecessary wavelength band to the outside, and widening the colorreproduction range of high-saturation, high-density portions.

Note that the present invention can be applied to an apparatuscomprising a single device or to system constituted by a plurality ofdevices.

Furthermore, the invention can be implemented by supplying a softwareprogram, which implements the functions of the foregoing embodiments,directly or indirectly to a system or apparatus, reading the suppliedprogram code with a computer of the system or apparatus, and thenexecuting the program code. In this case, so long as the system orapparatus has the functions of the program, the mode of implementationneed not rely upon a program.

Accordingly, since the functions of the present invention areimplemented by computer, the program code installed in the computer alsoimplements the present invention. In other words, the claims of thepresent invention also cover a computer program for the purpose ofimplementing the functions of the present invention.

In this case, so long as the system or apparatus has the functions ofthe program, the program may be executed in any form, such as an objectcode, a program executed by an interpreter, or script data supplied toan operating system.

Example of storage media that can be used for supplying the program area floppy disk, a hard disk, an optical disk, a magneto-optical disk, aCD-ROM, a CD-R, a CD-RW, a magnetic tape, a non-volatile type memorycard, a ROM, and a DVD (DVD-ROM and a DVD-R).

As for the method of supplying the program, a client computer can beconnected to a website on the Internet using a browser of the clientcomputer, and the computer program of the present invention or anautomatically-installable compressed file of the program can bedownloaded to a recording medium such as a hard disk. Further, theprogram of the present invention can be supplied by dividing the programcode constituting the program into a plurality of files and downloadingthe files from different websites. In other words, a WWW (World WideWeb) server that downloads, to multiple users, the program files thatimplement the functions of the present invention by computer is alsocovered by the claims of the present invention.

It is also possible to encrypt and store the program of the presentinvention on a storage medium such as a CD-ROM, distribute the storagemedium to users, allow users who meet certain requirements to downloaddecryption key information from a website via the Internet, and allowthese users to decrypt the encrypted program by using the keyinformation, whereby the program is installed in the user computer.

Besides the cases where the aforementioned functions according to theembodiments are implemented by executing the read program by computer,an operating system or the like running on the computer may perform allor a part of the actual processing so that the functions of theforegoing embodiments can be implemented by this processing.

Furthermore, after the program read from the storage medium is writtento a function expansion board inserted into the computer or to a memoryprovided in a function expansion unit connected to the computer, a CPUor the like mounted on the function expansion board or functionexpansion unit performs all or a part of the actual processing so thatthe functions of the foregoing embodiments can be implemented by thisprocessing.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application No.2008-068352 filed on Mar. 17, 2008, which is hereby incorporated byreference herein in its entirety.

1. An information processing method of generating print data in aprinting apparatus which forms an image on a printing medium with aplurality of types of printing materials, the method comprising: anacquisition step of acquiring light scattering characteristicinformation of all the printing materials used in the printingapparatus; a decision step of deciding, in accordance with the lightscattering characteristic information acquired in said acquisition step,an order in which the plurality of types of printing materials aresuperposed in at least some pixels of the image to be formed on theprinting medium; and a generation step of generating print data to formthe image on the printing medium by superposing the plurality of typesof printing materials in the order decided in said decision step,wherein, in said decision step, the plurality of types of printingmaterials are classified into a plurality of groups in accordance withthe light scattering characteristic information, and an order in whichthe printing materials are superposed to form the image on the printingmedium is decided in terms of the groups.
 2. The method according toclaim 1, wherein, in said decision step, the order is decided inaccordance with a light scattering characteristic represented by thelight scattering characteristic information acquired in said acquisitionstep, such that a printing material having a relatively high lightscattering characteristic is printed on a relatively lower layer.
 3. Themethod according to claim 1, wherein, in said acquisition step, piecesof the light scattering characteristic information of all the printingmaterials used in the printing apparatus are acquired by measuring, viaa measurement device, light scattering characteristics of patch imagesformed by discharging the plurality of types of printing materials ontothe printing medium.
 4. The method according to claim 1, wherein theprinting materials include a liquid, and in said acquisition step, thelight scattering characteristic information of the liquid printingmaterial or a diluted liquid of the printing material is acquired. 5.The method according to claim 1, wherein, in said acquisition step, alight scattering characteristic estimated from a composition of theprinting materials is acquired as the light scattering characteristicinformation.
 6. The method according to claim 1, wherein, in saiddecision step, the order in which the plurality of types of printingmaterials are superposed to form the image on the printing medium isdecided in accordance with the light scattering characteristicinformation for only a portion of the image having a color saturationhigher than a predetermined color saturation in each hue and eachbrightness in a color gamut reproducible by the printing apparatus. 7.The method according to claim 1, wherein, in said acquisition step,glossiness characteristic information of all the printing materials usedin the printing apparatus is acquired, and in said decision step, theorder in which the plurality of types of printing materials aresuperposed in at least some pixels of the image to be formed on theprinting medium is decided in accordance with the light scatteringcharacteristic information and glossiness characteristic informationacquired in said acquisition step.
 8. The method according to claim 1,wherein the plurality of types of printing materials include acombination of at least two types of printing materials having the samehue and different densities, and wherein a printing material having alow density in the combination of at least two types of printingmaterials having the same hue and different densities is printed on arelatively upper layer.
 9. The method according to claim 1, wherein theplurality of types of printing materials include at least one type ofprinting material of a spot color having a hue between arbitrary two ofprinting materials of cyan, magenta, and yellow basic colors, andwherein the printing material of the spot color is printed on arelatively upper layer compared with the printing materials of the basiccolors.
 10. The method according to claim 1, further comprising: adischarge step of causing a print-head having a plurality of nozzlearrays to discharge the plurality of types of printing materials to anentire width of a printing region in one direction, and a drive step ofcausing a main-scanning drive unit to execute main scanning by drivingat least either of the print-head and the printing medium.
 11. Themethod according to claim 10, wherein the image on the printing mediumis formed by executing the drive step N times (N is an integer of notless than 2) in a single region of the image, and in said decision step,a use ratio of each printing material used in each main scanning isdecided.
 12. The method according to claim 11, wherein, in said decisionstep, printing of a printing material on a relatively lower layer isdetermined to start in a relatively early execution of the N executionsof said drive step in the single region of the image.
 13. The methodaccording to claim 11, wherein, in said decision step, printing of aprinting material on a relatively lower layer is determined to completein a relatively early execution of the N executions of said drive stepin the single region of the image.
 14. The method according to claim 11,wherein, in said decision step, a print ratio of a printing materialprinted on a relatively lower layer is set high in a relatively earlyexecution of the N executions of said drive step in the single region ofthe image.
 15. A printing apparatus that forms an image on a printingmedium with a plurality of types of printing materials, the printingapparatus comprising: an acquisition unit configured to acquire lightscattering characteristic information of all the printing materials usedin the printing apparatus; a decision unit configured to decide, inaccordance with the light scattering characteristic information acquiredby said acquisition unit, an order in which the plurality of types ofprinting materials are superposed in at least some pixels of the imageto be formed on the printing medium; a generation unit configured togenerate print data for forming the image on the printing medium bysuperposing the plurality of types of printing materials in the orderdecided by said decision unit; and a printing unit configured to printbased on the print data, wherein said decision unit classifies theplurality of types of printing materials into a plurality of groups inaccordance with the light scattering characteristic information, anddecides an order in which the printing materials are superposed to formthe image on the printing medium in terms of the groups.
 16. Anon-transitory computer-readable medium for storing a program whichcauses a computer to execute an information processing method ofgenerating print data in a printing apparatus which forms an image on aprinting medium with a plurality of types of printing materials, themethod comprising: an acquisition step of acquiring light scatteringcharacteristic information of all the printing materials used in theprinting apparatus; a decision step of deciding, in accordance with thelight scattering characteristic information acquired in said acquisitionstep, an order in which the plurality of types of printing materials aresuperposed in at least some pixels of the image to be formed on theprinting medium; and a generation step of generating print data to formthe image on the printing medium by superposing the plurality of typesof printing materials in the order decided in said decision step,wherein, in the decision step, the plurality of types of printingmaterials are classified into a plurality of groups in accordance withthe light scattering characteristic information of the plurality oftypes of printing materials, and an order in which the printingmaterials are superposed to form the image on the printing medium isdecided in terms of the groups.